alt="Major triterpenes, cycloeucalenone and 31-norcyclolaudenone as inhibitors against both α-glucosidase and α-amylase in banana peel"/>
Cycloeucalenone and 31-norcyclolaudenone in banana peel have α-glucosidase and α-amylase inhibitory activities. The carbonyl group at C-3 and the double bond in the side chain of them are primary active sites in α-glucosidase and α-amylase inhibitory activities. And cycloeucalenone induced a parabolic mixed-type inhibition with a Ki value of 73.86 μM in the α-glucosidase inhibitory assay.
Summary
The inhibitory activities of banana peel extract against carbohydrate digestive enzymes were investigated. Cycloeucalenone and 31-norcyclolaudenone were obtained by bioassay-guided fractionation as effective inhibitors of α-glucosidase and α-amylase. The structure–activity relationships of four triterpenes isolated from banana peel, cycloeucalenone, 31-norcyclolaudenone and cycloeucalenol and its isomer were investigated. The IC50 values of cycloeucalenone and 31-norcyclolaudenone against α-glucosidase were 31.83 ± 2.46 μm and 38.85 ± 1.54 μm, respectively, and their IC50 values against α-amylase were 20.33 ± 0.59 μm and 27.63 ± 0.83 μm, respectively. In contrast, cycloeucalenol and its isomer had insufficient inhibitory activity against either enzyme. The primary active sites of cycloeucalenone and 31-norcyclolaudenone are the carbonyl group at C-3 and the double bond in the side chain. Cycloeucalenone induced a parabolic mixed-type inhibition with a Ki
value of 73.86 μm in the α-glucosidase inhibitory assay. This study provides new evidence for the potential use of banana peel triterpenes as antidiabetic agents.